Turning wrong snap judgement into positive

Malcolm Gladwell said in the Epilogue of his book, "Blink", that he was inspired to write the book by a wrong snap judgement and stereotype of a police officer who doubted him. I wonder how he could come up with a positive idea out of a negative experience that is completely because of other people's fault. I just wonder if I could do the same thing. At least, my recent experiences led me to read (actually listen to the audiobook of) "Blink" again.